[2+2] Cycloadditions with an Iron Carbene: A Critical Step in Enyne Metathesis

Area of Science:

• Organometallic Chemistry
• Catalysis
• Sustainable Chemistry

Background:

• Ruthenium carbene complexes are widely utilized in olefin metathesis and other applications.
• Iron carbene complexes with similar reactivity patterns have not been previously reported.
• Developing iron-based catalysts offers a more sustainable, cost-effective, and less toxic alternative to ruthenium.

Purpose of the Study:

• To synthesize a novel iron carbene complex.
• To investigate the reactivity of the synthesized iron carbene complex in cycloaddition reactions.
• To explore the potential of iron carbenes as sustainable alternatives in catalysis.

Main Methods:

• Synthesis of the iron carbene complex [{PC(sp²)P}Fe(N₂)(PMe₃)] using specific ligand systems.
• Reaction of the iron carbene complex with various alkynes to study cycloaddition.
• Characterization of reaction intermediates and products, including η³-vinyl carbenes.

Main Results:

• Successful synthesis of the iron carbene complex [{PC(sp²)P}Fe(N₂)(PMe₃)].
• Demonstration of [2+2] cycloaddition reactions between the iron carbene and alkynes, forming η³-vinyl carbenes.
• Observation of further reactivity of η³-vinyl carbenes with alkynes, leading to new iron carbene moieties.

Conclusions:

• The reported iron carbene complex exhibits reactivity analogous to ruthenium carbenes in [2+2] cycloaddition reactions.
• This work establishes a foundation for developing iron-based carbene chemistry, offering a sustainable alternative.
• The findings open new avenues for utilizing earth-abundant metals in catalytic transformations.